The present invention relates to the use of imide-containing aryl mono- and dihydroxy compounds as chain terminators and, respectively, monomer units for the production of polycarbonates, and also to polycarbonates comprising structures derived from imide-containing aryl hydroxy compounds, to processes for the production of the polycarbonates, to mouldings and extrudates obtainable from the said polycarbonates, and also to processes for the production of the mouldings and extrudates.
The high heat resistance of polycarbonates permits their use inter alia in sectors where they are likely to encounter high temperatures. Specific copolycarbonates (an example being a copolycarbonate based on bisphenol A and bisphenol TMC (1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane)) can give a further increase in heat resistance. The said polycarbonates are therefore also suitable for the production of lenses, reflectors, lamp covers and lamp housings, etc.
These materials do not only have to have good processability and good mechanical properties; they also have to satisfy other requirements, such as good surface quality in the resultant injection moulding, and also good adhesion to metal.
Heat resistance and mechanical properties can be varied widely as a function of the bisphenols used and of appropriate adjustment of the molecular weight of the homo- and copolycarbonates. However, the adhesion of the said polycarbonates to metal is often not ideal. Specifically in the reflectors sector, good adhesion to metal is essential.
Compounds used as chain terminators for the production of conventional polycarbonates are often monofunctional compounds based on phenol, examples being phenol, and 4-alkylphenols, such as p-tert-butylphenol, and 4-cumylphenol (Kunststoff-Handbuch [Plastics Handbook] 3; L. Bottenbruch, Hanser, Munich 1992, p. 127; EP-A 0 353 594).
Polyetherimide-containing polycarbonates are described in U.S. Pat. No. 4,393,190. These modified polycarbonates have improved chemicals resistance, but no mention is made of properties relating to adhesion to metal. The constitution of the polycarbonates or copolycarbonates described in the said document is moreover different than that of the copolycarbonates of the invention.
WO 00/37442 A1 describes polycarbonates having imide units. Here again, no mention is made of improved adhesion to metal. The constitution of the polycarbonates or copolycarbonates described in the said document is moreover different.
According to JP-A 07179594, nitro-functionalized polycarbonates exhibit improved properties of adhesion to metal. The said polymers are not the subject matter of this application.
U.S. Pat. No. 6,214,505 describes polycarbonates having imide units. However, the polycarbonates of the invention differ from these in having a different structure. U.S. Pat. No. 6,214,505 gives no details of surface properties.
DE 3834660 A1 describes the synthesis of etherimides. Again, the structure of these differs from that of the polycarbonates of the invention described here. There is no description of surface properties.
Plasma pre-treatment can sometimes alter the surface properties of polymers. Methods of this type are described by way of example by Friedrich et al. in Metallized plastics 5&6: Fundamental and applied aspects and H. Grünwald et al. in Surface and Coatings Technology 111 (1999) 287-296. However, surface treatment of plastics implies additional technical cost and can sometimes lead to damage to the plastics surface.
Various methods can be used to apply metals to the polymer, examples being vapour deposition or sputtering. There is a more detailed description of the processes by way of example in “Vakuumbeschichtung [Vacuum coating] Volumes 1 to 5”, H. Frey, VDI-Verlag Düsseldorf 1995 or “Oberflächen- and Dünnschicht-Technologie [Technology of surfaces and thin layers]” Part 1, R. A.